Re: ILE RPG calling ILE C

[Scott Klement <klemscot@xxxxxxxxxxxx>]

Hi James,

> I've got a problem with ILE RPG calling a procedure in ILE C. It seems
> that the return value (a character string of 4096 bytes) is being set
> properly in the C code (according to the dreaded ILE debugger), but it
> arrives completely blank in RPG (also according to the debugger). Is there
> something I need to do in the prototype for the procedure, so that RPG can
> find the return value?

Usually problems like this show up when you return a pointer from a C
function, but write your RPG prototype as if you were returning a string.

For example, if you have a C function like this:

       char *getstring(int key);

The RPG prototype must look like this:

     D getstring       PR              *   ExtProc('getstring')
     D   key                         10I 0 value

And then you call it like this:

     C                   eval      myString = %str(getstring(key))

I have a feeling that your RPG prototype looks like the following, which
will NOT work, unless the C function returns a data structure by value:

     D getstring       PR          4096A
     D   key                         10I 0 valu

If this is not the case, then please show us what your prototypes look like,
and if possible a little bit of the code, since you didn't give us much
information about how the data is being passed...